Phenylalanine Concentrations Research Articles

Saccadic reaction time and ocular findings in phenylketonuria

BackgroundPhenylketonuria (PKU) is an inherited metabolic disorder characterized by reduced activity of phenylalanine hydroxylase resulting in elevated blood phenylalanine (Phe) concentration. Despite some obvious ocular changes, the disorder has been poorly recognized by ophthalmologists. Neurophysiologic tests imply prolonged reaction time correlating with increased phenylalanine blood concentrations. We aimed to test saccadic reaction time in PKU patients in dependency of blood phenylalanine concentrations.MethodsNineteen biochemically diagnosed PKU patients and 100 controls completed comprehensive ophthalmologic and orthoptic examinations including saccadometry by infrared based video-oculography. Peak velocity, gain, and particularly latency of reflexive saccades were compared to controls, and regression analysis was performed.ResultsLatency of reflexive saccades was not associated with the current phenylalanine concentration. Although in 10 out of 19 patients phenylalanine concentrations were outside the age-related therapeutic range, latency differed little between PKU patients and the controls, as well as peak velocity and gain. Ocular findings occurred as partial hypopigmentation of the iris in one late diagnosed patient aged 36 years, and as bilateral cataracts (possibly due to steroid intake) with refractive amblyopia, strabismus, high myopia, and glaucoma in another late diagnosed patient aged 46 years. Visual acuity was reduced in eight PKU patients.ConclusionsSaccadometry, particularly saccadic reaction time, is not useful in the monitoring of phenylketonuria. Ophthalmic examination is recommended in PKU patients, as the occurrence of ocular pathologies was relatively high.

Phenylalanine: A Promising Inducer of Fruit Resistance to Postharvest Pathogens.

More than 40% of harvested fruit is lost, largely due to decay. In parallel, restrictions on postharvest fungicides call for eco-friendly alternatives. Fruit’s natural resistance depends mainly on flavonoids and anthocyanins—which have antioxidant and antifungal activity—synthesized from the phenylpropanoid pathway with phenylalanine as a precursor. We hypothesized that phenylalanine could induce fruit’s natural defense response and tolerance to fungal pathogens. The postharvest application of phenylalanine to mango and avocado fruit reduced anthracnose and stem-end rot caused by Colletotrichum gloeosporioides and Lasiodiplodia theobromae, respectively. The postharvest application of phenylalanine to citrus fruit reduced green mold caused by Penicillium digitatum. The optimal phenylalanine concentrations for postharvest application were 6 mM for citrus fruits and 8 mM for mangoes and avocadoes. The preharvest application of phenylalanine to strawberries, mangoes, and citrus fruits also reduced postharvest decay. Interestingly, citrus fruit resistance to P. digitatum inoculated immediately after phenylalanine application was not improved, whereas inoculation performed 2 days after phenylalanine treatment induced the defense response. Five hours after the treatment, no phenylalanine residue was detected on/in the fruit, probably due to rapid phenylalanine metabolism. Additionally, in vitro testing showed no inhibitory effect of phenylalanine on conidial germination. Altogether, we characterized a new inducer of the fruit defense response—phenylalanine. Preharvest or postharvest application to fruit led to the inhibition of fungal pathogen-induced postharvest decay, suggesting that the application of phenylalanine could become an eco-friendly and healthy alternative to fungicides.

Nutrient intake, body composition, and blood phenylalanine control in children with phenylketonuria compared to healthy controls

BackgroundPhenylketonuria (PKU) treatment consists of life-long protein restriction and Phe-free medical foods for adequate nutritional intake and growth. A relationship between body composition and blood phenylalanine (Phe) concentrations in subjects with PKU has been proposed but this has not been consistently reported. MethodsDietary intake, lean body mass (LBM) and fat mass (FM) were measured in 30 pediatric subjects with PKU compared to 30 age, and sex matched controls. The relationship between body composition and blood Phe was analyzed within the PKU cohort from clinically collected dried blood spot Phe concentrations. ResultsMale subjects with PKU had less LBM% and more FM% than controls (p = .024). There was no difference in LBM% and FM% among female subjects. Age (p = .02) and FM% (p = .02) were positively correlated to dried blood spot Phe. Synthetic protein intake (g/kg body weight) was negatively correlated with dried blood spot Phe (p = .04). Natural protein intake was not related to blood spot Phe. ConclusionsChildren with PKU face additional dietary challenges maintaining healthy growth and body composition while keeping Phe levels low. We observed higher FM% and lower LBM% in male subjects with PKU. Correlations do not prove cause and effect but suggest a relationship between increased blood Phe, lower synthetic protein intake and increased FM%. Future studies may explore if lower blood Phe concentrations is associated with a lower FM% and higher LBM%; particularly among adult patients now managed on pegvaliase (Palynziq®) who consume normal amounts of natural protein or among younger patients who consume glycomacropeptide (GMP).

Lysine and methionine supplementation in high soy protein content diets for silvery-black porgy (Sparidentex hasta) juveniles.

A two-month feeding trial was conducted to evaluate the effect of partial replacement of fish meal (FM) by soybean protein (SP) alone or in combination with lysine (Lys) and methionine (Met) supplementation in practical diets for silvery-black porgy juveniles (16.7±0.1 g). Seven isoproteic (ca. 50% crude protein) and isoenergetic (ca. 22.4 MJ kg-1) diets were formulated in which 45% (SP45), 60% (SP60) and 75% (SP75) of FM protein were replaced by SP and the control diet (FM) was prepared with FM as the major source of protein. In SP45+, SP60+ and SP75+ diets, 45 to 75% of FM was replaced by SP with supplementing blends of Lys and Met. Growth performance, feed utilization, and protein and lipid digestibility decreased with increasing dietary SP levels (p<0.05). Fish fed SP75 had the highest whole body lipid content, but with the lowest whole body arginine, lysine, histidine, phenylalanine and taurine concentrations (p<0.05). Supplementing Lys and Met in SP based diets did not improve growth performance, suggesting that the anti-nutritional factors in soybean protein products rather than Met and Lys deficiency might limit FM substitution with SP in silvery-black porgy juveniles.

Selenium nanoparticles induced variations in growth, morphology, anatomy, biochemistry, gene expression, and epigenetic DNA methylation in Capsicum annuum; an in vitro study

This study aimed to explore whether supplementation of the culture medium with selenium nanoparticles (nSe) can influence growth, biochemistry, expression of transcription factors, and epigenetic DNA methylation in Capsicum annuum. The seeds were grown in hormone-free MS culture medium supplemented with nSe (0, 0.5, 1, 10, and 30 mgL−1) or corresponding doses of bulk type selenate (BSe). Incorporation of nSe into the medium caused variations in morphology and growth in a manner dependent on the dose and Se type. The low doses of nSe displayed growth-promoting effects, whereas nSe at 10 and 30 mgL−1 were associated with severe toxicity and abnormality in leaf and root development. MSAP analysis confirmed the substantial variation in cytosine DNA methylation in response to the toxic dose of nSe exhibiting epigenetic modification. The nSe toxicity was associated with DNA hyper-methylations. The nSe treatments transcriptionally upregulated the bZIP1 transcription factor by an average of 3.5 folds. With a similar trend, the upregulation (mean = 9.8 folds) in the expression of the WRKY1 transcription factor resulted from the nSe application. The nSe0.5 or nSe1 treatments resulted in a significant induction (mean = 48%) in nitrate reductase activity. A high dose of nSe led to an increase in proline concentration. The nSe treatments were also associated with modifications in activities of peroxidase and catalase enzymes. Besides, the nSe utilization increased the activity of phenylalanine ammonia-lyase enzyme (mean = 76%) and concentrations of soluble phenols (mean = 51%). The toxic dose of nSe also caused abnormalities in the structure of the stem apical meristem. The nSe toxicity was also associated with inhibition in the differentiation of xylem tissues. These findings provide novel insights into the nSe-associated molecular variations in conferring the modified growth, anatomy, and metabolism.

Development of an inventory to assess perceived barriers related to PKU treatment

BackgroundAccording to studies of phenylketonuria (PKU), the Brazilian population’s metabolic control shows unsatisfactory indexes from childhood. Research on patients’ perceived difficulties or barriers to adherence to treatment can help us to comprehend how these outcomes are associated. The present study aimed to: (1) describe the development of an inventory for identifying the most frequent and relevant perceived barriers to PKU treatment from the perspective of patients, caregivers, and healthcare professionals; (2) evaluate certain psychometric characteristics of the new measure; and, (3) explore potential predictors (sociodemographic and medical characteristics) that may contribute to increasing the number of perceived barriers and examine whether the number of barriers is associated with the degree of adherence shown by the patient.ResultsParticipants in the study were 23 patients with PKU (M age = 18.0 years; SD = 7.3; range 6 to 34 years; 69% early-treated) in classical (n = 11) and mild (n = 12) form, and 11 caregivers. The inventory, developed to ascertain perceived barriers to treatment, was completed by patients (≥ 13 years) and caregivers of patients aged 6 to 17 years. Analyses were conducted to investigate whether barrier inventory scores were associated with adherence to treatment as measured by phenylalanine levels in patients’ medical records. Scores on the inventory differed across the patient age groups: adolescents had lower scores (i.e. reported fewer barriers) compared with those of adults (U = 8.000, p = 0.008); patients with better recent metabolic control also reported fewer perceived barriers than did patients with poor adherence (U = 20.000, p = 0.009); and the number of perceived barriers was positively associated with recent blood phenylalanine concentration (Kendall’s taub = 0.41; p = 0.001).ConclusionsThese results suggest that the inventory has merit in assessing perceived barriers and support the need for further research on barriers perceived by PKU patients.

A Review on Electrochemical Sensors and Biosensors Used in Phenylalanine Electroanalysis.

Phenylalanine is an amino acid found in breast milk and in many foods, being an essential nutrient. This amino acid is very important for the human body because it is transformed into tyrosine and, subsequently, into catecholamine neurotransmitters. However, there are individuals who were born with a genetic disorder called phenylketonuria. The accumulation of phenylalanine and of some metabolites in the body is dangerous and may cause convulsions, brain damage and mental retardation. Determining the concentration of phenylalanine in different biologic fluids is very important because it can provide information about the health status of the individuals envisaged. Since such determinations may be made by using electrochemical sensors and biosensors, numerous researchers have developed such sensors for phenylalanine detection and different sensitive materials were used in order to improve the selectivity, sensitivity and detection limit. The present review aims at presenting the design and performance of some electrochemical bio (sensors) traditionally used for phenylalanine detection as reported in a series of relevant scientific papers published in the last decade.

Soybean bioactive peptides supplementation during late gestation and lactation affect the reproductive performance, free amino acid composition in plasma and milk of sows

The objective of this study was to determine the effects of soybean bioactive peptides (SBP) supplementation to sows during late gestation and lactation on plasma and milk free amino acid composition and reproductive performance. A total of 86 gestating sows (Landrace × × Yorkshire; mean parity of 2.40 [SD 1.18]) from two successive batches of with a 9-day interval were randomly assigned to either a basal diet group (control diet [Con]) or the Con supplemented with 2% soybean bioactive peptides (SBP) product group from d 90 of gestation to weaning at day 21 of lactation. The duration of farrowing and the interval between piglet births (P < < 0.05) were decreased and the litter weight gain during lactation (P = 0.097) tended to increase of sows fed SBP than Con diet. Serum concentrations of lysine, phenylalanine, valine, arginine (+36–354%, P < < 0.05) and leucine (+30%, P = 0.056), glutamate (+36%, P = 0.057), ornithine (+104%, P = 0.079) at farrowing were increased or tended to increase of sows fed SBP. Serum concentrations of methionine (+29%, P < 0.05), lysine (+72%, P = 0.068), isoleucine (+35%, P = 0.074), arginine (+45%, P = 0.098) and ornithine (+99%, P = 0.085) on postpartum day 21 were increased or tended to increase of sows fed SBP. The concentrations of cystathionine, lysine, arginine, glutamine (+92~351%, P < 0.05), alanine (+191%, P = 0.061) in colostrum and arginine (+41%, P < 0.05) in milk were increased or tended to increase of sows fed SBP. The contents of IgG and fat in colostrum (P < 0.05) of sows fed SBP were increased compared with that in Con sows. Serum malondialdehyde concentrations of sows at parturition and at d 14 of lactation were both markedly (P < 0.05) decreased and the activity of total antioxidant capacity in serum of sows at parturition (P < 0.05) was significantly increased with SBP supplementation. In conclusion, the present research indicated that dietary supplementation with soybean bioactive peptides during late gestation and lactation could shorten the duration of farrowing and enhance the growth performance of suckling piglets by improving functional amino acids concentration and antioxidant properties.

Nanomechanical Properties and Phase Behavior of Phenylalanine Amyloid Ribbon Assemblies and Amorphous Self-Healing Hydrogels.

Phenylalanine was the minimalistic and first of numerous nonproteinaceous building blocks to be demonstrated to form amyloid-like fibrils. This unexpected organization of such a simple building block into canonical architecture, which was previously observed only with proteins and peptides, has numerous implications for medicine and supramolecular chemistry. However, the morphology of phenylalanine fibrils and their mechanical properties was never characterized in solutions. Here, using electron and atomic force microscopy, we analyze the morphological and mechanical properties of phenylalanine fibrils in both air and fluids. The fibrils demonstrate an exceptionally high Young's modulus (up to 30 GPa) and are found to be composed of intertwined protofilaments in a helical or twisted ribbon morphology. In addition, X-ray scattering experiments provide convincing evidence of an amyloidal cross-β-like secondary structure within the nanoassemblies. Furthermore, increasing the phenylalanine concentration results in the formation of highly homogenous, noncrystalline, self-healing hydrogels that display storage and loss moduli significantly higher than similar noncovalently cross-linked biomolecular nanofibrillar scaffolds. These remarkably stiff nanofibrillar hydrogels can be harnessed for various technological and biomedical applications, such as self-healing, printable, structural, load-bearing 3D scaffolds. The properties of this simple but quite remarkable hydrogel open a possibility to utilize it in the biomaterial industry.

An Untargeted Metabolomics Investigation of Jiulong Yak (Bos grunniens) Meat by 1H-NMR.

Yak represents the main meat source for Tibetan people. This work aimed to investigate the metabolome of raw meat from Jiulong yaks, focusing on specimens farmed and harvested locally through traditional procedures. Untargeted nuclear magnetic resonance spectroscopy (1H-NMR) was selected as the analytical platform. Samples from longissimus thoracis, trapezius, triceps brachii and biceps femoris muscles, with different prevalences of red and white fibers, were selected. Among the fifty-three metabolites quantified in each of them, carnitine, carnosine, creatine and taurine are known for their bioactive properties. Twelve molecules were found to be differently concentrated in relation to muscle type. Longissimus thoracis, compared to biceps femoris, had higher concentrations of carnosine and formate and lower concentrations of mannose, inosine, threonine, IMP, alanine, valine, isoleucine, tyrosine, phenylalanine and leucine. A metabolic pathway analysis suggested that the main pathways differing among the muscles were connected to the turnover of amino acids. These results contribute to a deeper understanding of yak raw meat metabolism and muscle type differences, which can be used as an initial reference for the meat industry to set up muscle-specific investigations. The possibility of simultaneously quantifying several bioactive compounds suggests that these investigations could revolve around meat’s nutritional value.

Acetylation of Phenylalanine Hydroxylase and Tryptophan 2,3-Dioxygenase Alters Hepatic Aromatic Amino Acid Metabolism in Weaned Piglets.

Weaning significantly alters hepatic aromatic amino acid (AAA) metabolism and physiological functions. However, less is known about the regulating mechanism of hepatic AAA metabolism after weaning. A total of 200 21-day-old piglets (Duroc × Landrace) were assigned randomly to the control group and the weaning group. In this study, weaning significantly decreased the concentration of phenylalanine, tryptophan, and tyrosine in piglet livers (p < 0.05). Additionally, through the detection of liver AAA metabolites and metabolic enzyme activity, it was observed that hepatic tryptophan catabolism was enhanced, while that of phenylalanine was weakened (p < 0.05). Intriguingly, acetyl-proteome profiling of liver from weaned piglets showed that weaning exacerbated the acetylation of phenylalanine hydroxylase (PAH) and the deacetylation of tryptophan 2,3-dioxygenase (TDO). Analysis of PAH and TDO acetylation in Chang liver cells showed that acetylation decreased the PAH activity, while deacetylation increased the TDO activity (p < 0.05). Furthermore, metabolites of AAAs and the acetylation statuses of PAH and TDO in primary hepatocytes from weaned piglets were consistent with the results in vivo. These findings indicated that weaning altered the PAH and TDO activity by affecting the acetylation state of the enzyme in piglets’’ livers. Lysine acetylation may be a potential regulatory mechanism for AAA metabolism in response to weaning.

Dried blood spot versus venous blood sampling for phenylalanine and tyrosine

BackgroundThis study investigated the agreement between various dried blood spot (DBS) and venous blood sample measurements of phenylalanine and tyrosine concentrations in Phenylketonuria (PKU) and Tyrosinemia type 1 (TT1) patients.Study designPhenylalanine and tyrosine concentrations were studied in 45 PKU/TT1 patients in plasma from venous blood in lithium heparin (LH) and EDTA tubes; venous blood from LH and EDTA tubes on a DBS card; venous blood directly on a DBS card; and capillary blood on a DBS card. Plasma was analyzed with an amino acid analyzer and DBS were analyzed with liquid chromatography-mass spectrometry. Agreement between different methods was assessed using Passing and Bablok fit and Bland Altman analyses.ResultsIn general, phenylalanine concentrations in LH plasma were comparable to capillary DBS, whereas tyrosine concentrations were slightly higher in LH plasma (constant bias of 6.4 μmol/L). However, in the low phenylalanine range, most samples had higher phenylalanine concentrations in DBS compared to LH plasma. Remarkably, phenylalanine and tyrosine in EDTA plasma were higher compared to all other samples (slopes ranging from 7 to 12%). No differences were observed when comparing capillary DBS to other DBS.ConclusionsOverall agreement between plasma and DBS is good. However, bias is specimen- (LH vs EDTA), and possibly concentration- (low phenylalanine) dependent. Because of the overall good agreement, we recommend the use of a DBS-plasma correction factor for DBS measurement. Each laboratory should determine their own factor dependent on filter card type, extraction and calibration protocols taking the LH plasma values as gold standard.

Caring for a Child with Phenylketonuria: Parental Experiences from a Eurasian Country.

Phenylketonuria (PKU) and mild hyperphenylalaninemia (HPA) are characterized by increased blood phenylalanine concentrations varying from mild to severe. Management of PKU was reported to be time consuming and burdensome for caregivers. This study intended to explore the experiences of families caring for a child with PKU/HPA in a country with a high PKU rate. The aim of this study was to compare parental well-being between parents of children with and without dietary restrictions and to explore the factors associated with parental psychological well-being. Participants were interviewed about their experiences, concerns, and challenges related to the disease by using a semistructured questionnaire. After the interview, parents filled out the Beck Depression Inventory and State-Trait Anxiety Inventory-Trait. This study highlighted the adverse psychological, financial, and social effects of the diagnosis and management of the disease regarding the lives of the families of children with PKU/HPA. Although parental anxiety scores of children with and without dietary restrictions were similar, depressive symptom scores were higher in parents of children with dietary restrictions. However, in multiple regression analysis, lower household income and absence of perceived social support were found to be independent factors associated with higher depressive symptom scores. Having a daughter diagnosed with PKU/HPA and lower household income were found to be factors associated with higher anxiety scores. This study revealed that income level, perceived social support, and gender of the child were factors associated with psychological well-being of parents caring for children with PKU/HPA. Health care professionals should identify the challenges faced by families and should be aware of risk factors associated with lower parental well-being to achieve better family adjustment and better health outcomes.

Vaginal metabolome: towards a minimally invasive diagnosis of microbial invasion of the amniotic cavity in women with preterm labor

Microbial invasion of the amniotic cavity (MIAC) is only identified by amniocentesis, an invasive procedure that limits its clinical translation. Here, we aimed to evaluate whether the vaginal metabolome discriminates the presence/absence of MIAC in women with preterm labor (PTL) and intact membranes. We conducted a case-control study in women with symptoms of PTL below 34 weeks who underwent amniocentesis to discard MIAC. MIAC was defined as amniotic fluid positive for microorganisms identified by specific culture media. The cohort included 16 women with MIAC and 16 control (no MIAC). Both groups were matched for age and gestational age at admission. Vaginal fluid samples were collected shortly after amniocentesis. Metabolic profiles were analyzed by nuclear magnetic resonance (NMR) spectroscopy and compared using multivariate and univariate statistical analyses to identify significant differences between the two groups. The vaginal metabolomics profile of MIAC showed higher concentrations of hypoxanthine, proline, choline and acetylcholine and decreased concentrations of phenylalanine, glutamine, isoleucine, leucine and glycerophosphocholine. In conclusion, metabolic changes in the NMR-based vaginal metabolic profile are able to discriminate the presence/absence of MIAC in women with PTL and intact membranes. These metabolic changes might be indicative of enhanced glycolysis triggered by hypoxia conditions as a consequence of bacterial infection, thus explaining the utilization of alternative energy sources in an attempt to replenish glucose.

Intracellular Metabolites in Marine Microorganisms during an Experiment Evaluating Microbial Mortality.

Metabolomics is a tool with immense potential for providing insight into the impact of biological processes on the environment. Here, we used metabolomics methods to characterize intracellular metabolites within marine microorganisms during a manipulation experiment that was designed to test the impact of two sources of microbial mortality, protozoan grazing and viral lysis. Intracellular metabolites were analyzed with targeted and untargeted mass spectrometry methods. The treatment with reduced viral mortality showed the largest changes in metabolite concentrations, although there were organic compounds that shifted when the impact of protozoan grazers was reduced. Intracellular concentrations of guanine, phenylalanine, glutamic acid, and ectoine presented significant responses to changes in the source of mortality. Unexpectedly, variability in metabolite concentrations were not accompanied by increases in microbial abundance which indicates that marine microorganisms altered their internal organic carbon stores without changes in biomass or microbial growth. We used Weighted Correlation Network Analysis (WGCNA) to identify correlations between the targeted and untargeted mass spectrometry data. This analysis revealed multiple unknown organic compounds were correlated with compatible solutes, also called osmolytes or chemical chaperones, which emphasizes the dominant role of compatible solutes in marine microorganisms.

An Approach for In Situ Rapid Detection of Deep-Sea Aromatic Amino Acids Using Laser-Induced Fluorescence.

Amino acids are the material basis of almost all life activities. An improved understanding of the source, state, and cycle of amino acids is essential for determining the energy flow and material circulation of marine ecosystems. In the present study, an in situ rapid detection method of ultraviolet (UV; 266 nm) laser-induced fluorescence (LIF) technology was used to detect three natural, aromatic amino acids in the seawater. The laser-induced fluorescence peaks of aromatic amino acids tryptophan, tyrosine, and phenylalanine were located at 350 nm, 300 nm, and 280 nm, respectively. High, linear correlations between the concentrations of the aromatic amino acids and the fluorescence peak heights were observed, and the lowest detectable concentrations of tryptophan, tyrosine, and phenylalanine were 4.70 × 10−9 mol/L, 2.76 × 10−8 mol/L, and 6.05 × 10−7 mol/L, respectively, which allowed us to quantify their concentrations by using laser-induced fluorescence. This paper not only provides a practical method for the detection of aromatic amino acids in seawater, but a new means to further understand the biogeochemical processes of carbon cycles in the deep sea.

Differentiation of fresh and thawed Atlantic salmon using NMR metabolomics

NMR metabolomics approach was used to distinguish fresh and thawed Atlantic salmon. Statistical analysis revealed significant differences in the concentration of some metabolites in reference and frozen-thawed fish during its storage. It was found that salmon freezing/thawing caused a significant increase in the concentration of fumarate and phenylalanine in stored salmon muscle. The concentration of fumarate increased until the 3rd–5th day after thawing and then gradually decreased, reaching zero after two weeks of storage. The concentration of phenylalanine was constantly increased during the storage time. Furthermore, it was detected that aspartate was formed in the flesh of only thawed fish after the second day of storage. Its concentration followed the same trend as fumarate reaching its maximal concentration on the 3rd–5th day after thawing (up to 3.8 mg in 100 g of muscle) and gradually decreased to zero. Aspartate formation was influenced by storage time after thawing and not by the time after slaughter. We propose to use the formation of aspartate in stored salmon flesh as a marker of salmon freezing/thawing.

Amino Acids of Seminal Plasma Associated With Freezability of Bull Sperm.

Sperm cryopreservation is an important technique for fertility management, but post-thaw viability of sperm differs among breeding bulls. With metabolites being the end products of various metabolic pathways, the contributions of seminal plasma metabolites to sperm cryopreservation are still unknown. These gaps in the knowledge base are concerning because they prevent advances in the fundamental science of cryobiology and improvement of bull fertility. The objective of this study was to test the hypothesis that seminal plasma amino acids are associated with freezability of bull sperm. To accomplish this objective, amino acid concentrations in seminal plasma from seven bulls of good freezability (GF) and six bulls of poor freezability (PF) were quantified using gas chromatography–mass spectrometry (GC–MS). Multivariate and univariate analyses were performed to identify potential freezability biomarkers. Pathways and networks analyses of identified amino acids were performed using bioinformatic tools. By analyzing and interpreting the results we demonstrated that glutamic acid was the most abundant amino acid in bull seminal plasma with average concentration of 3,366 ± 547.3 nM, which accounts for about 53% of total amino acids. The other most predominant amino acids were alanine, glycine, and aspartic acid with the mean concentrations of 1,053 ± 187.9, 429.8 ± 57.94, and 427 ± 101.3 nM. Pearson’s correlation analysis suggested that phenylalanine concentration was significantly associated with post-thaw viability (r = 0.57, P-value = 0.043). Significant correlations were also found among other amino acids. In addition, partial least squares-discriminant analysis (PLS-DA) bi-plot indicated a distinct separation between GF and PF groups. Phenylalanine had the highest VIP score and was more abundant in the GF groups than in the PF groups. Moreover, pathway and network analysis indicated that phenylalanine contributes to oxidoreductase and antioxidant reactions. Although univariate analysis did not yield significant differences in amino acid concentration between the two groups, these findings are significant that they indicate the potentially important roles of amino acids in seminal plasma, thereby building a foundation for the fundamental science of cryobiology and reproductive biotechnology.

Quantitative metabolomics of saliva using proton NMR spectroscopy in patients with Parkinson's disease and healthy controls.

Parkinson's disease (PD) is a multisystem disorder of unknown etiology, highlights a broad array of symptoms and pathological features influencing organs throughout the body. The metabolic profile of saliva in patients with PD may be influenced by malabsorption in the gastroenteric tract, neurodegeneration, and mitochondrial dysfunction. In the present study, we apply a powerful NMR metabolomics approach for biomarker identification in PD using saliva, a non-invasive bio-fluid. Metabolic profiling of saliva were studied in patients with PD (n = 76) and healthy controls (HC, n = 37) were analyzed and differentiated PD from HC. A total of 40 metabolites including aromatic amino acids, short-chain fatty acids, branched chain amino acids, taurine, and N-acetylglutamate were identified. Spectral binned data and concentration of metabolites were estimated for analysis. Increased concentration of phenylalanine, tyrosine, histidine, glycine, acetoacetate, taurine, TMAO, GABA, N-acetylglutamate, acetoin, acetate, alanine, fucose, propionate, isoleucine, and valine were observed in PD as compared to HC. Further, subgroup analysis among early PD, advanced PD, and HC groups, revealed increased metabolite concentration in early PD group as compared to advanced PD and HC group. Analysis revealed potential biomarkers and their involvement in amino acid metabolism, energy metabolism, neurotransmitters metabolism, and microflora system. Patients with early PD exhibited higher metabolite concentration as compared to advanced PD group which might be associated with dopaminergic treatment. The results of our data indicate that patients with PD might be characterized by metabolic imbalances like gut microflora system, energy metabolites, and neurotransmitters which may contribute to the PD pathogenesis.

Metabolism of Amino Acids in the Brain and Their Roles in Regulating Food Intake.

Amino acids (AAs) and their metabolites play an important role in neurological health and function. They are not only the building blocks of protein but are also neurotransmitters. In the brain, glutamate and aspartate are the major excitatory neurotransmitters, whereas γ-aminobutyrate (GABA, a metabolite of glutamate) and glycine are the major inhibitory neurotransmitters. Nitric oxide (NO, a metabolite of arginine), H2S (a metabolite of cysteine), serotonin (a metabolite of tryptophan) and histamine (a metabolite of histidine), as well as dopamine and norepinephrine (metabolites of tyrosine) are neurotransmitters to modulate synaptic plasticity, neuronal activity, learning, motor control, motivational behavior, emotion, and executive function. Concentrations of glutamine (a precursor of glutamate and aspartate), branched-chain AAs (precursors of glutamate, glutamine and aspartate), L-serine (a precursor of glycineand D-serine), methionine and phenylalanine in plasma are capable of affecting neurotransmission through the syntheses of glutamate, aspartate, and glycine, as well as the competitive transport of tryptophan and tyrosine across from the blood-brain barrier. Adequate consumption of AAs is crucial to maintain their concentrations and the production of neurotransmitters in the central nervous system. Thus, the content and balance of AAs in diets have a profound impact on food intake by animals. Knowledge of AA transport and metabolism in the brain is beneficial for improving the health and well-being of humans and animals.